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(N0 Mdel.)

W. D. GRIMSHAW.

' IN$ULATING ELEGTRIGAL CONDUCTOR-S AND COMPOUND FOR (BOATING THE SAME.

No. 308,890. v Patented Dec. 9, 1884.

WITNESSES \NVENTUR M. w/wwu 2W" W I UNITED STATES PATENT OFFICE.

WILLIAM D. GRIMSHAV, OF NEW" YORK, N. Y., ASSIGNOR TO THE GRIM- SI-IAWV INSULATED VIBE AND CABLE MANUFACTURING COMPANY, OF

SAME PLACE.

INSULATING ELECTRICAL CONDUCTORS AND COMPOUND FOR COATING THE SAME.

SPECIFICATION forming part of Letters Patent No. 308,890, dated December 9, 1884.

(No model.)

To all whom it may concern:

Be it known that I, WILLIAM D. Gum- SHAW, of the city, county, and State of New York, have invented certain new and useful Improvements in Insulating Electrical Oonductors and in Compounds for Coating the Same,of which the following is a specification.

My invention relates to electrical conductors; and it has for its object to provide an effectual and durable insulation for such c011- ductors. This I accomplish by covering the conductor with materials, the details of which will be hereinafter fully set forth, and also by the peculiar construction of the electrical conductor.

In the drawings, Figure l is a perspective View of my improved conductor, representing the wire or conductor covered with the insulating compositions. Fig. 2 is a erossseetional view of the same.

Similar letters denote like parts.

a represents a conductor of any suitable material.

1) represents the covering, which I apply next to the wire or conductor, and which I preferably apply in strips.

0 c is an exterior insulation of a different composition from that of b, which I preferably apply in two strips.

(1 is the extreme outside covering, and eonsists of tape which is applied in the process of manufacture to keep the insulating compositions together in proper shape during the process of vulcanization. It acts, however, as an additional safeguard both in insulating and protecting the conductor.

\Vhile I use any suitable material for my conductor, I prefer a copper or steel center, with an outer coating next to the first insulation'of tin or its equivalent, the special advantage of tin-coated wire being that it will not easily oxidize.

The covering 1), I call the neutral wall, and it is a non-vulcanized insulator. Preferably it is composed of about forty per cent. of rubber, fourteen per cent. of whiting, twenty per cent. of litharge, and twenty-six per cent. of magnesia, or their equivalents.

The exterior insulation, 0 c, is coating,

' consisting, preferably, oftwenty-six percent.

of rubber, twenty-four per cent. of whit/lug, twenty percent. of litharge, four of lamp-black, two per cent. ot sulphur, and twenty-four per cent. of magnesia.

The tape (1 is made of ordinary muslin, which is first spread with the composition last-named, giving it four or five coats, as in the ordinary way of manufacturing waterproof goods. This muslin is then eut into tape, which is afterward passed through a bath or thin cold solution of the composition last named. I pass the tape through the solution, that the rough and raw edges of the fiber of thetapemay be sealed and thoroughly saturated. This tape dries very quickly after it has passed through the solution, and is then ready for use.

The heavy black insulation 0 c is a composition prepared in the same manner as compositions are made which are used in rubber goods. It is prepared in large sheets and then passed through a cutting-machine to be cut into strips.

The inner core or neutral wall is prepared in the same way as the insulation 0 c. This neutral wall is almost a perfeetinsulator. The

exterior insulation, 0 c, is in a plastic state when it is put on the conductor. I apply these various insulating-coverings by means of machinery, which I will not particularly describe, as I have made it the subject of an application for Letters Patent of the United States of even date herewith. The strips of the neutral wall I) are wound on reels, from which they are deposited 011 the wire, as shown in Fig. I. The exterior insulation, 0 c, is, alter being cut in strips, wound 011 reels and ap plied longitudinally, as shown in Fig. 1. The tape d is also applied from reels, as above described, and forms a waterproof envelope or overcoat, as it were. After the wire is thoroughly dry this outside protecting-covering might be stripped oil, when the use of the insulated conductor is such as not toneed such protection. In some instances the neutral wall b alone might be applied directly to the conduetor, without the addition of the external insulation, 0 (1', and tape (Z. I preferably use p the materials which I use and by the method the outside protecting covering (2, as it is of great Value, as I have stated, during the process of manufacture to keep in place the insulating compositions. A very good insulat ed conductor may be made, however, without its use. After I have applied the neutral wall, the external insulation, and outside covering, b, as described, the conductor wound on a reel is placed within preferably a steam-heated Vulcanizer, and there kept from one to four hours, according to the thickness of the external insulation, until the same is cured. The reel on which the conductor is wound is kept in constant motion while within the vulcanizer, that the coating of the conductor may not be displaced while in a plastic state.

The great advantage of my electrical conductor, made as described, is that I am enabled cheaply and quickly to produce a conductor having avulcanized outside coating with a non-vulcanized neutral wall between the external insulation and the conductor it self.

It is of the highest importance that the conductor be kept bright and free from oxidation, and I am able to attain this result by in which I apply the same.

I am well aware that conducting-wires have before my invention been covered with pure india-rubber, and that this india-rubber has then been covered with an india-rubber eoinr pound prepared for vulcanization. I do not, therefore, broadly claim this method.

I am also well aware that electrical conductors have before my invention been covered with various insulating compounds.

\VhatI do claim as new, and desire to secure by Letters Patent, is

1. An insulated electrical conductor consisting ofa wire or any suitable material, covered first, spirally, with strips of a composition of rubber, whiting, litharge, and magnesia, and then longitudinally by strips of a vulcanized compound consisting of 1'ubber,whiting, litharge, lamp-black, sulphur, and magnesia, the whole protected by an external covering or insulation of tape, substantially as described.

2. lhe method of manufacturing the abovedescribed electrical conductor, consisting in first spirally covering a conductor with an unvulcanized material in strips, as described, forming a neutral wall, and in surrounding this neutral wall with the Vulcanizable insulating material in longitudinal strips, and with tape, as described, and then vulcanizing the same, substantially as described.

In witness whereof I have hereunto set my hand.

\V. I). GRIMSILXW.

.Vitnesses:

NM. 13. II. DowsE, WM. T. GILBERT. 

